Environmental Protection Agency Administrator Scott Pruitt says a two-year delay in a sweeping Obama-era water regulation will put farmers and ranchers at ease. But a wave of looming litigation, coupled with potential legal vulnerabilities in the delay, threatens to upend that prospect.

New York is poised to lead a group of states in contesting the delay, which the EPA and the Army Corps of Engineers finalized in late January. And environmental groups are signaling they’re preparing to join the fight.

The Obama administration put its update to the Clean Water Act into effect in August 2015, and like-minded policymakers and advocates continue to tout the regulation as critical for safe drinking water, as well as fish and wildlife. The Waters of the United States regulation expanded the reach of federal jurisdiction over bodies of water, such as streams and wetlands, by 3 percent, according to Obama’s EPA.

Now, New York Attorney General Eric Schneiderman is vowing to take President Trump’s EPA to court. “The Trump Administration’s suspension of these vital protections is reckless and illegal,” he said in a statement. “That is why I will lead a multistate coalition that will sue to block this rollback.”

Nine other states, including California and the District of Columbia, joined New York in opposing the EPA’s delay proposal, but haven’t yet thrown their hats in the legal ring.

In interviews with National Journal, high-profile environmental lawyers signaled they’re ready to join the fray. Jon Devine, senior attorney for the Natural Resources Defense Council’s water program, said the group intends to file suit in the near future, and Earthjustice attorney Janette Brimmer said litigation is a “strong probability.”

The delay “was completely illogical,” Devine said. “It made no reasonable sense. The agencies claim to be taking this action to ensure clarity and consistency across the country and [are] planning to return to a situation, a set of policies, that were notoriously unclear and inconsistent across the country.”

The landmark 1972 Clean Water Act is weighed down by ambiguous language, fueling long-running battles over the EPA’s regulatory authority. A patchwork of regulations, Supreme Court decisions, and agency legal interpretations guided EPA water policy until 2015, and continues to do so today.

That’s because the states—including Oklahoma when Pruitt was state attorney general—and industry groups like the American Farm Bureau Federation fought tooth and nail against implementation of the regulation in the courts. A North Dakota circuit court stayed the rule for 13 states in 2015, and the 6th Circuit Court of Appeals slapped down a nationwide stay the same year. But a Supreme Court decision roughly two weeks ago instructed district courts to first field suits over the regulation. That puts the 6th Circuit stay in jeopardy, leaving a large part of the country subject to the Obama-era regulation.

The statute authorizes regulation of “navigable waters,” and stakeholders continue to lock horns over the extent to which tributaries, such as ponds and streams, are eligible. Farmers and ranchers, along with developers and other industry leaders, say the 2015 regulation and ensuing litigation created severe uncertainty about how to handle the water on farm fields and pastures. Those industries, already beset by financial troubles, say they don’t want to put in place sanitation measures unless they know they’re necessary.

Failure to pass legislation to hone that authority continues to perpetuate the legal limbo.

A rewrite of the Obama-era regulation is likely to surface by April or May, Pruitt told senators last week.

But the two-year delay contains glaring legal defects that imperil its near-term future, Bill Buzbee, a professor at Georgetown University Law School, told National Journal.

“There’s a ton of law that talks about what agencies need to do if they want to change a finalized, promulgated regulation, and the basics of it [are] they can’t do it like this. They cannot just render it a dead letter without justifying that decision,” he said.

Opponents of the Obama-era regulation, however, are vowing to dig in the legal battle as well. Delaying this rule would provide more certainty, they contend, by preventing the short-term implementation of the 2015 regulation that would soon be replaced by a more industry-friendly Pruitt rewrite.

“EPA is in middle of a regulatory process to relook at whether the rule should be repealed and whether it should be revised, and it would be foolish, it would create a whole lot of upheaval for the states and the regulated communities to implement while you’re in the middle of this process,” Ellen Steen, general counsel at the American Farm Bureau Federation, said.

The EPA declines to comment on pending litigation.

Most Republicans side with industry opponents of the regulation, vehemently arguing the regulation marks one of the most egregious examples of Obama-era federal overreach.

“The Obama administration’s outrageous Waters of the United States rule would have put backyard ponds, puddles, and farm fields under Washington’s control,” John Barrasso, the top Republican on the Senate environment committee, said the day the EPA finalized the delay. He added that “this delay gives the Trump administration time to revise this rule.”

Meanwhile, the EPA is forging ahead with the new rule in the wake of months of outreach. Environmental groups say they received short shrift in that process, but farmers and ranchers are buoyant with Pruitt at the helm.

“It would be great if the rule would regulate things that look like water and a person of reasonable intelligence can at least have an inkling that they might have a federal water of the U.S. on their land by looking at it,” Steen said. “That would be really refreshing.”

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